Inhibition of corrosion of metals



United States Patent 'ce 3,412,024 INHIBITION OF CORROSION 0F METALS James R. Stanford, Houston, Tex., assignor to Nalco Chemical Company, Chicago, 111., a corporation of Delaware No Drawing. Filed Apr. 7, 1964, Ser. No. 358,119 7 Claims. (Cl. 2522-855) This invention, in general, relates to new chemicals; new corrosion inhibiting compositions useful in preventing or minimizing corroson of iron or steel tubing, other well parts, and the like which come in contact with corrosive sweet and sour crude oils, especially those containing corrosive brines recovered with the oil; and to methods of inhibiting such corrosion.

An object of the invention is to provide new compounds useful, for example, in inhibiting corrosion of metal equipment in oil and gas wells.

Another object of the invention is to provide chemicals for use in preventing corrosion of pipe or equipment which is in contact with a corrosive oil-containing medium in oil wells, refineries or the like.

Still a further object of the invention is to provide corrosion-inhibiting chemicals for protecting metals in systems which are subject to contact by various corrosive agents such as carbon dioxide, aqueous or nonaqueous solutions of carbon-dioxide, hydrogen sulfide, aqueous or nonaqueous solutions of hydrogen sulfide, brines, weak inorganic acids and organic acids.

A still further object is to provide methods of inhibiting corrosion of ferrous metals in contact with said corrosive media with the aforesaid chemicals.

An additional object of the invention is to provide new and improved corrosion inhibiting compositions which are readily adsorbed by metal surfaces. Other objects will appear hereinafter.

The new chemicals of the invention comprise alkylbenzene sulfonic acid salts of partial amides of organic polyamines and acyclic monocarboxylic acids and polycarboxylic acids containing 1-48 carbons and an acyclic chain which is either saturated or olefinically unsaturated. The acids further may comprise in part cyclic carboxylic acids, notably rosin acids, such as rosin acids existing in crude tall oil, the chief rosin acid of which is abietic acid. The partial amide is one in which at least one but less than all of the amino groups of the polyamine are arnidified with the carboxylic acid or acids. At least one and up to all of the basic, nonamidified amino groups of the partial amide form amine salt groups with the alkylbenzene sulfonic acid when the sulfonic acid is mixed with the partial amide. The alkyl group of the alkylbenzene sulfonic acid should have 8-16 carbons, dodecylbenzene sulfonic acid being the preferred species.

The polyamines may be polyalkylene polyamines having 3 to about 10 amino groups and 2-6 carbon alkylene groups. There are a number of mixtures of these polyamines commercially available at reasonable costs. The polyamine may also be an aminoalkyl derivative of a basic N-heterocycle such as N-aminoalkyl piperazines wherein the alkyl group has 2-6 carbons and aminoalkyl homologs thereof wherein the N-substituent has the formula, H(HN---R) wherein R is the alkylene group of 2-6 carbons and x is a small whole number greater than one. The sulfonic acid salts form on a basic nitrogen of said compounds.

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3,412,024 Patented Nov. 19, 1968 In addition to the foregoing salts, the invention also embraces corrosion inhibiting compositions comprising mixtures of said partial amide salts and 10l50%, based on the weight of said salts, of free acyclic acids as aforedefined in pure form, in admixture with each other, or in admixture with rosin acids, e.g., crude tall oil.

Embodiments of the invention are illustrated in the following examples, wherein the parts or percentages stated are by weight unless otherwise stated. For sake of brevity, certain compounds or compositions in the examples are identified by trade name. These compounds are:

(1) Century D-1475 acid is a mixture of vegetable oil fatty acids (essentially C -C fatty acids) having an acid value of 188-203, a saponification value of 190-210 and an iodine value of 40-50.

(2) Century D- acid is a mixture of polymerized vegetable fatty acids containing a major proportion of dimerized and trimerized linoleic and linolenic acids and having an acid value of 155-169, a saponification value of 186-192, and an iodine value of 40-48. Century D- acid is a similar mixture of polymerized vegetable fatty acids containing a high percentage of trimer. It has a saponification value of a range from -148 and an iodine range of 42-50.

(3) Emery 3363D acid is a mixture of polybasic acids derived from natural fats and oils. The acid mixture has an average of about two carboxyl groups per molecule, an acid value of 208, a saponification value of 252, and an iodine value of 11.

(4) Emery 3362B acid is a blend of low molecular weight acids of the fatty acid series from formic acid through heptanoic acid with formic acid in preponderance. The blend has an acid value of 690.

(5) TX-3650 is a mixture of organic acids obtained as a wax oxidate and having a saponification number of 440450 and a neutralization number of 225-250.

(6) Amine AL-l is a mixture of N-aminoethyl-piperazine, N-hydroxyethylpiperazine, N-aminoethylethanolamine and higher homologs of these compounds. The mixture has a total nitrogen content of 29.730.8% and a titratable amine content of 16.4 meg./ gm.

(7) Emfac 1202 is a pelargonic acid which is the normal C fatty acid, having an acid value of 345-360 and an iodine value of 1 maximum.

EXAMPLE I In a three-necked reaction vessel equipped with a stirrer, a Dean-Stark trap, a condenser and a thermometer, there were added, in parts by weight, parts of crude tall oil, 75 parts of a mixture of polyethylene polyamines containing polyethylene polyamines of the series H N- (RNH) H wherein the polyethylene polyamines are higher homologs than tetraethylene pentamine (Polyamine H Solid, Union Carbide and Carbon), and 50 parts of S0 extract, an aromatic hydrocarbon solvent. The mixture was heated to 150 C. Aqueous distillate was removed from the heated reaction mixture in a period of fifteen minutes in an amount of about 10.5 parts, the temperature rising to about 250 C. The resultant amide reaction product in the solvent was cooled to 150 C and another 200 parts of S0 extract were added.

After the product cooled to about 80 C., it was stirred and blended with the following chemicals in the order stated:

(l) 290 parts of dodecylbenzene sulfonic acid.

(2) 580 parts of Emery 3363--D Acid.

(3) 810 parts of S extract.

(4) 58 parts of methanol.

35 parts of polyoxyethylated phenol formaldehyde resin (nonylphenol-formaldehyde resin consisting of approximately 43% resin with the balance polyoxyethylene groups.

(6) 23 parts of an emulsion breaker, containing a blend of an ethoxylated nonyl phenol resin with a mixed ester of an oxyalkylated tripentaerythrital monoester.

EXAMPLE II The procedure of Example I was repeated with 270 parts of Century D-1475 Acid, 100 parts of diethylene triamine and 50 parts of S0 extract. The aqueous distillate began to distill over at about 160 C. Thirty-seven parts of aqueous distillate were removed in a 23 minute period, during which the temperature rose to about 250 C.

After adding 200 parts of S0 extract, the following were blended therewith in the order stated:

( 1) 350 parts dodecylbenzene sulfonic acid. (2) 230 parts of Century D-85 Acid.

(3) 1830 parts S0 extract.

(4) 230 parts isopropyl alcohol.

(5) 7 parts emulsion breaker of Example I.

EXAMPLE III The procedure of Example I was repeated with 125 parts of crude tall oil, 25 parts of the aforedescribed Emery 3363-D Acid, 50 parts of the aforedescribed Polyamine H Solid, and 50 parts of S0 extract. The aqueous distillate began to distill over at about 167 C. Ten and one-half parts of aqueous distillate were collected in a 10-minute period, during which the temperature rose to 250 C. After cooling and adding 200 parts of S0 extract, the following were added in the order stated:

( 1) 91 parts of dodecylbenzene sulfonic acid.

(2) 91 parts of Emery 3363-D Acid.

(3) 238 parts of S0 extract.

(4) 45 parts of isopropyl alcohol.

(5) 18 parts of polyoxyethylated phenolformaldehyde resin of Example I.

(6) 4 parts of an emulsion breaker of Example I.

The corrosion protection values in the following tables were determined by semi-dynamic corrosivity tests, also known as corrosion inhibitor wheel tests. The degree of protection to be expected from corrosion inhibitors in the produced fluids from oil and gas wells can be evaluated by these tests. They further indicate the minimum dosage at which inhibitors are capable of laying down and maintaining protective films under laboratory condi tions simulating well conditions, especially those where inhibitor application is continuous or semicontinuous.

This test evaluates the corrosivity of produced fluids by determining weight loss of metal specimens exposed in sealed vessels containing the fluids. The sealed vessels are mounted on a wheel or mounting-board and maintained under constant rotation and temperature throughout the exposure period.

The effectiveness of inhibitors is rated by comparing weight losses of similar specimens in inhibited and uninhibited samples of fluid.

Procedure Test cells are filled with fresh fluids at the same oil/ water ratio as exists in the field samples. (If a sizeable vapor space exists in the sample bottles as received, the fluids in the bottles are purged with inert gas to remove oxygen. The purged samples then are saturated with carbon dioxide, if they are from sweet gas condensate wells, or are saturated with hydrogen sulfide, if they are from sour wells.)

Inhibitors for evaluation are introduced into the test cells at various dosages. Control test cells containing no chemical also are used, to establish a base corrosion rate from which relative percent protection provided by the chemicals can be computed. All tests normally are run in duplicate.

Weighed metal specimens are inserted and the test cells mounted on a rotating wheel. The sealed test vessels are maintained under constant temperature and rotation rate throughout the exposure.

Following exposure, the specimens are removed, degreased in acetone or benzene and then scrubbed with soap and water. If corrosion products adhere to the surface, they are removed by dipping the coupons in inhibited technical-grade hydrochloric acid. After cleaning, the coupons are immersed in alcohol, then in acetone or benzene, dried and reweighed.

(wt. loss uninhibited-wt. loss with inhibitor) wt. loss uninhibited X =percent protection General test conditions are as follows:

(1) Volume of test cells 200 ml. (about 0.4 pint). (2) Surface area of specimen per unit volume 11.41 sq. ftJbbl. (1 cm.

15 ml.)maximum.

Room temp. to 200 F.

Mild steel plate or carbon steel rod.

(5) Surface of specimen Sandblasted (plate) or polished (rod).

(6) Exposure period 24 hours.

(7) Rotation rate 24 r.p.m.

Corrosion rates determined in this test typically are in excess of rates encountered in the field. This acceleration and magnification of corrosive attack shows up differences between chemicals and thus is an effective screening procedure.

Experience indicates that the following rough correlation exists between corrosivity ratings on this test and actual corrosivity of fluids in the field:

TABLE Ia Weight loss in this test: Typical corrosiveness in field Less than 10 milligrams Mild 10-20 Moderate More than 20 Severe The following rough correlations also appear to exist between percent protection as furnished by inhibitors in this laboratory test, and the performance of the inhibitors in the field:

TABLE lb Protection by inhibitor in lab tests:

Inhibitor performance in' field 90% or more Excellent 75% to 89% Good 50% to 74% Fair Less than 50% Poor The tests in the following examples were conducted at about 160 F. with mild steel plate for about 24 hours in a 50/50 volume mixture of sweet brine and kerosene saturated with CO unless otherwise indicated.

EXAMPLE IV In the equipment described in Example I, parts of crude tall oil, 65 parts of Amine AL-l and 50 grams of about F. with mild steel plate for about 24 hours in utes. Nine parts of aqueous distillate were distilled off. The resultant ester-amide was diluted with 200 parts of toluene after it cooled. The resultant amide-ester solution, hereafter abbreviated A.E.S., was tested in the same 50/50 CO saturated kerosene sweet brine corrosive mixture as a corrosion inhibitor in the following compositions.

TABLE IL-CORROSION RESULTS Percent Protection at Concentration in p.p.m.

l and '-*=Dodecylbenzene sulfonic acid and substitute S01 extract, respectively.

EXAMPLE v 15 In the equipment described in Example I, 150 parts of crude tall oil, 65 parts of Amine AL1 and 50 parts of substitute S extract were heated to 243 C. in a period of a fatty acid mixture (Emfac 1202), 100 parts of diof 73 minutes. Eleven parts of water were distilled 01f. ethylene triamine, and 100 parts of S0 extract were The cooled amide-ester mixture was diluted with 200 20 heated to 240 C. in 15 minutes. The aqueous distillate parts toluene. The resultant ester-amide solution was was 30 parts of water. Upon cooling, the partial amide blended at a ratio of 300 parts of said solution with 225 was blended with 400 parts of substitute S0 extract. The parts of dodecylbenzene sulfonic acid and 150 parts of amide solution was blended at a ratio of 100 parts of said substitute S0 extract. This product is hereafter desigsolution and 54 parts of dodecylbenzene sulfonic acid. nated Blend. 25 The final pH was about 6.0.

Corrosion test results were:

EXAMPLE VII In the equipment described in Example I, 162 parts TABLE IIL-CORROSION RESULTS Composition in Parts By Weight I0 20 30 40 O p.p.m. p.p.m. p.p.m. p.p.m. p.p.m.

Blend (all) 21 57 79 80 45 Blend, 5 Caprylie acid. 41 25 38 79 85 45 Blend, 5 Capric acidl. 10 33 74 89 87 45 Blend, 5 Laurie acid 18 20 60 83 92 45 Blend, 5 Palmitic acid. 33 78 90 90 45 Blend, 5 Century D-14 12 73 89 93 91 45 Blend, 5 Crude tall oil 14 22 74 87 88 45 Blend, 5 Century D-75 17 70 82 88 9O 45 Blend, 5 TX 3650 Acid 11 37 91 92 93 45 Blend, 5 Acirltol FA-l. 12 19 72 89 90 4O Blend, 10 Caprylic Acid 16 14 70 75 75 40 Blend, 10 Palrnitic acid 12 11 56 83 81 EXAMPLE VI The resultant blend is designated in Table V as Blend. In equipment described in Example I, a mixture of 45 The results of the corrosion tests were:

Composition in Parts By Weight lo 50 p.p.m. p.p.m. p.p.m. p.p.m. p.p.m.

Blend (all) 0 18 26 39 35 Blend, 5 Laurie acid 10 16 33 27 35 45 Blend, 5 Century D-1475 Aci 3 14 42 96 98 S 135 parts of Century D 1475 Acld (vegetable fatty acid EXAMPLE VH1 parts of diethylene triamine and 50 parts of substitute S0 extract was heated to 240 C. in 18 minutes. Seven- Using the equipment described in Example I, a mixteen parts of water were distilled off. The cooled reaction ture of 135 parts of Century D-l475 Acid, 66 parts of mixture was diluted with 200 parts toluene. dipropylenel,2-triamine and 50 parts of substitute S0 Two hundred parts of the resultant solution were extract were heated to 242 C. in 20 minutes. Twentyblended with 113 parts of dodecylbenzene sulfonic acid. three parts of aqueous distillate were distilled over. Upon The pH of the blend was about 6.0. The product is descooling, the partial amide was diluted with 200 parts of ignated in Table IV as Blend. toluene. The amide solution was blended at a ratio of The corrosion test results were: 100 parts of said solution with 40 parts of dodecycl- 45 Blend, 5 Laurie acid 5 30 66 92 45 Blend, 5 Century D-1475 Acid 2 48 77 93 95 benzene sulfonic acid. The blend is designated in Table VI as Blend.

The results of the corrosion tests were:

TABLE VI.-CORROSION RESULTS nitrogens, substantially all of which are in the form of amine salt groups with said alkylbenzene sulfonic acids, said amines selected from the group consisting of poly- Percent Protection at Concentration in p.p.m.

Composition in Parts By Weight 10 20 30 40 50 p.p.m. p.p.m. p.p.m. p.p.m. p.p.m.

Blend (all) 1 20 37 48 64 45 Blend, 5 Laurie acid 18 35 47 81 45 Blend, Century D-147 0 21 39 88 93 EXAMPLE IX Using the equipment described in Example I, a mixture of 162 parts of Emfac 1202, 131 parts of dipropylene-1,2-triamine and 100 parts of substitute S0 extract were heated to 240 C. in 30 minutes. Forty-six parts of aqueous distillate were distilled over. Upon cooling, the partial amide was diluted with 400 parts of toluene. The amide solution was blended at a ratio of 100 parts of said solution with 52 parts of dodecylbenzene sulfonic acid. The blend is designated in Table VII as Blend.

The results of the corrosion tests were:

TABLE VII.CO RROSION RESULTS Percent Protection at Concentration in p.p.m.

Composition in Parts By Weight 10 20 30 40 50 p.p.m. p.p.m. p.p.m. p.p.m. p.p.m.

Blend (all) 1 17 21 37 45 Blend, 5 Laurie acid 1 19 19 25 45 Blend, 5 Century D-1475 Acid 3 11 25 44 91 EXAMPLE X free higher fatty acids consist essentially of dimer fatty In equipment described in Example I, a mixture of 150* parts of crude tall oil, 65 parts of Amine AL-l and 50 parts of substitute S0 extract was heated to 243 C. in 14 minutes. There were 10 parts of aqueous distillate. Upon cooling, the product was blended with 300 parts of substitute S0 extract.

The product was blended at a ratio of 100 parts of the solution with 51 parts of dodecylbenzene sulfonic acid. The blend is designated in Table VIII as Blend.

The corrosion results were:

TABLE VIII.CO EROSION RESULTS acids.

4. Compositions as claimed in claim 1 wherein said free higher fatty acids consist essentially of dimer fatty acids and trimer fatty acids.

5. A method for inhibiting corrosion of ferrous metals in contact with corrosive media in corrosive oil compositions recovered from a subterranean formation which comprises treating said metals with oil containing corrosion inhibiting compositions comprising as the active, corrosion inhibiting compounds (A) salts of (a) alkyl- Percent Protection at Concentration in p.p.m.

Composition in Parts By Weight 10 20 30 40 p.p.m p.p.m. p.p.m. p.p.m. p.p.m.

Blend (all) o 14 32 as 47 45 Blend, 5 Laurie acid 0 13 33 38 45 Blend, 5 Century D-1475 Aci 0 15 34 s1 87 The corrosion inhibiting chemicals and compositions 55 benzene sulfonic acids having 8-16 carbon alkyl groups herein disclosed are dispersed or dissolved in the produced and (b) partial amides of at least one of monomeric, difluids at concentrations ranging from 10 to 100,000 p.p.m. meric and trimeric higher fatty acids and organic amines Corrosion inhibition may be achieved by either a conhaving a plurality of basic nitrogens, substantially all of tinuous low concentration of inhibitor being in contact which are in the form of amine salt groups with said alkylwith the metal to be protected, or by using a high conbenzene sulfonic acids, said amines selected from the centration of inhibitor in a batch or squeeze type treatgroup consisting of polyalkylene polyamines having 3-10 ment. When the chemical is applied continuously the amino groups and 2-6 carbon alkylene groups and N- concentration of inhibitor in the fluid falls within the aminoalkyl substituted piperazines wherein the aminopreferred range of 10 to 500 p.p.m. When the chemical alkyl group has the formula H(HNR-) wherein R is used in a squeeze or batch type treatment the preis an alkylene group of 2-6 carbons and x is a small ferred range falls within 10,000 to 100,000 p.p.m. To those skilled in the art it will be apparent that the squeeze applications gives long term protection with single treatments.

The invention is hereby claimed as follows:

1. Corrosion inhibiting compositions wherein the active, corrosion inhibiting compounds consist essentially of (A) salts of (a) alkylbenzene sulfonic acids having 8-16 carbon alkyl groups and (b) partial amides of at least one of monomeric, dimeric and trimeric higher fatty acids and organic amines having a plurality of basic whole number, and (B) 10-150% by weight, based on said salts, of at least one of monomeric, dimeric and trimeric free higher fatty acids to provide corrosion inhibiting films on said metals.

6. A method as claimed in claim 5 wherein said free higher fatty acids consist essentially of dimer fatty acids.

7. A method as claimed in claim 5 wherein said free higher fatty acids consist essentially of dimer fatty acids and trimer fatty acids.

(References on following page.)

l0 Riggs et a1. 2528.55 Wirtel et a1. 2528.5S, Kirkpatrick et al. 252-8.55 Suprin et a1. 252-389 Sheldahl 2528.55

HERBERT B. GUYNN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,412,024 November 19, 1968 James R. Stanford It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 66, "40" should read 48 Signed and sealed this 21st day of April 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Attesting Officer 

1. CORROSION INHIBITING COMPOSITIONS WHEREIN THE ACTIVE, CORROSION INHIBITING COMPOUNDS CONSIST ESSENTIALLY OF (A) SALTS OF (A) ALKYLBENZENE SULFONIC ACIDS HAVING 8-16 CARBON ALKYL GROUPS AND (B) PARTIAL AMIDES OF AT LEAST ONE OF MONOMERIC, DIMERIC AND TRIMERIC HIGHER FATTY ACIDS AND ORGANIC AMINES HAVING A PLURALITY OF BASIC NITROGENS, SUBSTANTIALLY ALL OF WHICH ARE IN THE FORM OF AMINE SALT GROUPS WITH SAID ALKYLBENZENE SULFONIC ACIDS, SAID AMINES SELECTED FROM THE GROUP CONSISTING OF POLYALKYLENE POLYAMINES HAVING 3-10 AMINO GROUPS AND 2-6 CARBON ALKYLENE GROUPS AND N-AMINOALKYL SUBSTITUTED PIPERAZINES WHEREIN THE AMINOALKYL GROUP HAS THE FORMULA H(HNR-)X WHEREIN R IS AN ALKYLENE GROUP OF 2-6 CARBONS AND X IS A SMALL WHOLE NUMBER, AND (B) 10-150% BY WEIGHT, BASED ON SAID SALTS, OF AT LEAST ONE OF MONOMERIC, DIMERIC AND TRIMERIC FREE HIGHER FATTY ACIDS. 